With the current low prices for servers and the need for processing power, even a small company may end up with quite a few of them. If ten years ago it was still common to see an entire company using just one server, these days that's no longer the case.
New computers are added to the network with the understanding that they will be taken care of by the admins. Keeping an eye on these servers is a tedious, time-consuming process. Even with 5 minutes per server (to check the logs and other parameters), it may take an hour to make sure that everything is ok and no "red lights" are blinking on any of the servers.

Comments:EventID.Net
According to Microsoft, this event is logged when a store is dismounted. This can be caused by an administrative action inside of Exchange System Manager (ESM). Additionally, this could be due to a problem where the drive has filled up or the database exceeded the 16-GB size limit (Standard Edition only). See MSEX2K3DB for more details on this event.